Silicon carbide (SiC) diodes have been widely recognized for their significant advantages in power applications, especially under high voltage/temperature conditions. In general, SiC Schottky diodes are advantageous because of low onset voltage (as compared with that of SiC p-n diodes) and no reverse recovery. However, reverse leakage current of a planar Schottky diode can be significantly larger under high blocking voltage, caused by tunneling effects at the Schottky interface.
Junction barrier Schottky (JBS) diode structure was proposed to address this problem, which combines the advantages of Schottky junction and PN junction diodes. In JBS structure, a plurality of P regions are disposed between Schottky regions. The depletion layer diffuses from PN junction to exhibit pinch-off below the Schottky contact in reverse blocking mode, which can provide an electric field shielding effect. As a result, the electric field strength at the Schottky interface can be reduced and the diode leakage current can be decreased accordingly.
The electric field shielding effect can be enhanced by increasing the PN junction depth. However, due to the strong lattice of SiC material, the ion implantation depth is usually restricted to less than 1 μm. Recently, a trench type junction barrier Schottky diode structure with trenches totally surrounded by P regions is proposed as shown in FIG. 4. With the introduction of the trench, P-type ions can be implanted into the sidewall and bottom of the trench, and the resulting PN junction can be deeper than 1 μm. However, the channel resistance between adjacent deep P regions will be increased since only the upper Schottky contact between the P regions can conduct current in the normal forward manner. As a result, the forward performance of the device will be sacrificed. Therefore, there remains a need for a new and improved trench type junction barrier Schottky diode to overcome the problems stated above.